Pneumatic tool

Abstract

A pneumatic tool (20) for impacting a workpiece (22) is provided. The tool (20) comprises a casing (42) defining a chamber (48). A piston (54) is slidable within the chamber (48) along an operational axis (A). An exhaust valve (100) controlled by a pilot valve (200) slides the piston (54) by selectively introducing and releasing pressurized fluid into and out from the chamber (48). A tool bit (24) is slidable within the chamber (48) to impact the workpiece (22). Kinetic energy is transferred to the tool bit (24) from the piston (54) via an impact from the piston (54) as the piston (54) slides within the chamber (48). An energy absorbing mechanism (402) reduces the kinetic energy of the tool bit (24) after impact by the piston (54). The energy absorbing mechanism comprises a sleeve (404) that slides along the casing (42) and first (412) and second (414) pressure chambers that dissipate the kinetic energy of the tool bit (24) in multiple stages.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of U.S. provisional patent application Ser. Nos. 60 / 430,611, filed Dec. 3, 2002; 60 / 430,550, filed Dec. 3, 2002; and 60 / 430,610, filed Dec. 3, 2002, all of which are herein incorporated by reference.FIELD OF THE INVENTION[0002]The present invention generally relates to a pneumatic tool having an impactor device, e.g., piston and tool bit, for impacting a workpiece. More specifically, the present invention relates the pneumatic tool having an energy absorbing mechanism for absorbing kinetic energy of the impactor device during use to prevent the destruction of components of the pneumatic tool, such as during a dry fire, while otherwise providing a high impacting force to the workpiece.BACKGROUND OF THE INVENTION[0003]Pneumatic tools offer a “best-fit” solution in many applications because of their safety, reliability, and simplicity. Typically, however, pneumatic tools for impacting a workpiece by delive...

AI Technical Summary

Benefits of technology

[0006]The present invention provides a tool for impacting a workpiece. The tool comprises a casing having a proximal end and a distal end with a chamber defined therebetween. An impactor device is slidable within the chamber along an operational axis. A valve system slides the impactor device within the chamber by selectively introducing and releasing fluid pressure into and out from the chamber. An energy absorbing mechanism reduces kinetic energy of the impactor device as the impactor device slides within the chamber. The energy absorbing mechanism comprises a sleeve that slides along the casing and first and second pressure chambers to reduce the kinetic energy of the impactor device. The first pressure chamber is defined between the impactor device and the sleeve and the second pressure chamber is defined between the casing and the sleeve. The first pressure chamber reduces the energy of the impactor device in a first stage immediately after movement thereof by compressing pressurized fluid within the first pressure chamber. The second pressure chamber reduces the energy of the impactor device in a second stage after compression in the first pressure chamber and when the impactor device impacts the sleeve.

[0007]The present invention yields several advantages over the prior art. For instance, two pressure chambers are provided to reduce the kinetic energy of the impactor device as the impactor device slides in the casing. As a result, energy dissipation occurs in at least two stages. In the first stage, the energy of the impactor device is dissipated primarily by compressing pressurized fluid in the first pressure chamber between the impactor device and the sleeve. In the second stage, after the impactor device impacts the sleeve, the energy of the impactor device is dissipated primarily by compressing pressurized fluid in the second pressure chamber. This multi-stage approach to energy dissipation using multiple pressure chambers reduces the potentially destructive hammering forces that may otherwise be experienced in a pneumatic tool such as one that absorbs kinetic energy in a single stage by directly impacting a energy absorbing component of the tool. Furthermore, the multi-stage approach to energy dissipation balances a need for smaller, more maneuverable tools with the need for high kinetic energies. Using two pressure chambers provides a more compact tool design. At the same time, the two pressure chambers prolong the kinetic energy dissipation such that the impactor device can still perform high-energy work.

Problems solved by technology

Typically, however, pneumatic tools for impacting a workpiece by delivering hammering blows, e.g., pneumatic hammers, have characteristics that detract from their utility or preclude their use in some applications such as breaking off casting risers on a production line, or seating large press-fit assemblies.

However, some applications, such as breaking off casting risers on a production line, require the impactor device to carry high kinetic energy throughout a relatively long stroke to impact workpieces at varying distances.

In such an event, without an energy absorbing mechanism, tool components can be subjected to large destructive forces.

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